不同收割强度对菹草(Potamogeton crispus)生长和光合荧光特性的影响

Effect of harvesting intensity on the growth and photosynthetic fluorescence characteristics of Potamogeton crispus

在水深为1.5 m的水道中,研究了不同收割强度(0、15、30、45、60、75、90和105 cm)对菹草生长和光合荧光特性的影响.结果表明:(1)收割对菹草枝条生长和恢复影响显著.对照组(0 cm)株高最大,并在水面形成冠层.15 cm组在实验第20 d恢复,30～105 cm组恢复率分别为69.67%、17.78%、8.83%、5.33%、2.28%和1.90%.(2)收割显著降低了菹草的生物量.与对照组相比,收割组鲜重增加量分别下降了23.71%、54.90%、81.19%、85.82%、90.72%、94.07%和95.10%.15～105 cm收割组最终生物量则分别下降为对照组的59.36%、43.16%、27.69%、18.73%、14.66%、8.14%和4.07%.(3)收割使菹草营养繁殖体(石芽)数量、个体大小和鲜重显著降低.(4)中、低强度收割对菹草叶片最大光化学量子产量(Fv/Fm)影响不明显,而高强度收割组(尤其是105 cm)Fv/Fm显著下降.菹草叶片快速光响应曲线ETRmax差异不显著;中、低强度收割组ETRmax略有上升,而高强度收割组ETRmax出现下降.由结果可知,收割对控制菹草生物量和繁殖体数量效果明显,但以中、低收割强度为宜.

To determine the impacts of cutting on the growth and photosynthetic fluorescence characteristics of Potamogeton crispus, apexes of the plant were cut with different cutting intensities（0, 15,30, 45, 60, 75,90 and 105cm） in a pool depth of 1. 5 m. Results show that： Cutting significantly affected the growth and recovery of the shoot of P. crispus. The plant height of the control group（ 0 cm） was maximum and had formed canopy on the surface of water. The group of 15 cm restored on the twentieth day of the experiment. The recovery rates of the groups from 30 cm to 105 cm were 69.67% , 17.78% , 8.83% , 5.33% , 2.28% and l. 90% , respectively ; Cutting significantly reduced the biomass of P. crispus. Comparing with the control group, the increment of fresh weight of the cutting groups decreased by 23.71% , 54.90% , 81.19% , 85.82% , 90.72% , 94.07% and 95.10% , respectively. The final hiomass of the cutting groups from 15 cm to 105 em declined to 59.36% , 43.16% , 27.69% , 18.73% , 14.66% , 8.14% and 4.07% of the control group, respectively; Cutting has significantly reduced the quantity of the brood bud and the size of each individual and the fresh weight of P. crispus ; Cutting with medium and low intensity did not have obvious impact on the leaves of Fv/Fm of P. crispus, but Fv/Fm of high intensity cutting groups（ especially 105 cm） has significant impact. The maximal relative electron transport rate（ ETR max ）of the leaves rapid light curves had no significant difference. The groups with medium and low intensity increased slightly while the ETRmax of high intensity cutting groups declined. The experimental results show that cutting had obvious effect on controlling biomass of P, crispus and numbers of brood buds, but medium and low cutting intensity was less obvious.